Cystiscus

Cystiscus is a taxonomic genus of minute sea snails, marine gastropod mollusks or micromollusks.

Cystiscus
Cystiscus yasawaensis
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Clade: Caenogastropoda
Clade: Hypsogastropoda
Clade: Neogastropoda
Family: Cystiscidae
Subfamily: Cystiscinae
Genus: Cystiscus
Stimpson, 1865[1]
Type species
Cystiscus capensis
Synonyms

This genus was placed in the family Cystiscidae by Coovert and Coovert, 1995. Previously the genus was in the family Marginellidae, where it is still placed by many other malacologists.

Diagnosis

Shell minute to small, white, hyaline; spire immersed to low; lip thickened, smooth or weakly denticulate; external varix absent; siphonal notch absent; posterior notch absent; lacking collabral parietal callus ridge; columella multiplicate, with combined usually 2 to 8 plications plus parietal lirae, first plication usually strong and raised. Mantle smooth, at least partially extending over external shell surface.

Shell description

Shell minute to small (adult length 1–6 mm). Color white, hyaline; surface smooth, glossy. Shape usually elliptic, obovate, or subtriangular; weakly shouldered. Spire completely immersed to low. Aperture narrow to broad, usually wider anteriorly. Lip slightly to distinctly thickened, flared posteriorly in some species, smooth on inside edge to weakly denticulate, lacking lirae, external varix absent. Shell lacking a siphonal notch and posterior notch. Shell with weak parietal callus wash or weak parietal callus deposits in some species, but lacking collabral parietal callus ridge. Columella multiplicate, with combined total 2 to 8 plications plus parietal lirae, rarely to 17 in which the posteriormost are denticles; one species with only 1 plication. Plications usually occupying less than half the length of the aperture, but most of the aperture in some. Plications excavated just inside aperture in a few species, usually evenly rounded, first plication usually raised and very strong. Shell with cystiscid internal whorls.

Animal anatomy

Internal: Unknown
External: Animal with eyes at side of head, usually on lateral swelling; mantle smooth, at least partially extending onto external shell surface, in some species nearly covering shell; foot relatively narrow, about as wide as shell length; head and mantle usually uniformly colored, often bright red, orange, or yellow, or brown, or black, internal mantle color pattern often showing through translucent shell.
Radula: Uniserial, ribbon long, narrow, composed of 80-209 plates. Rachidian plates overlapping, narrow, moderately to strong arched, with 6-14 sharp cusps on posterior edge, the central cusp usually the strongest. The anterior edge of the rachidian plate is strongly concave, resulting in U- or V-shaped plates.

Habitat

Intertidal to 370 m.

Fossil record

Eocene of France and Alabama, upper Oligogene and Miocene of Western Atlantic, to Recent.

Remarks

The two halves of the head are capable of closing together at will, thus appearing unsplit. The long siphon usually distinguishes this group from Gibberula. The shell of Persicula is usually patterned, often has a distinct external varix, and the spire is usually immersed. These conchological features serve to separate the two groups.

Species

Cystiscus contains the following accepted species:[2]

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References
  1. Stimpson, W. (1865). "On certain genera and families of zoophagous gasteropods". American Journal of Conchology. 1: 55–64, pl. 8-9. Retrieved 18 July 2020.
  2. "Cystiscus". WoRMS. World Register of Marine Species. Retrieved 2018-12-17.
  3. Crosse, Joseph Charles Hippolyte (1870). "Diagnoses molluscorum novorum". Journal de Conchyliologie. 18: 301–304. Retrieved 12 July 2020.
  4. Tomlin, John Read le Brockton (1918). "Descriptions of three new new species of Marginella from South Africa, with a note on M. sutoris Dunker". Journal of Conchology. 15: 306–307, pl. 10.
  5. Boyer, F. (2003). "The Cystiscidae (Caenogastropoda) from upper reef formations of New Caledonia". Iberus. 21 (1): 241–272. Retrieved 13 June 2020.
  6. Wakefield, A.; McCleery, T. (2006). "Descriptions of new species of Pacific Cystiscus Stimpson, 1865 (Gastropoda : Cystiscidae). Part 1: species with banded mantle patterns". Novapex (Hors-série 4). 7: 1–31.
  7. Bavay, A. (1917). "Quelques coquilles des sables littoraux de divers pays". Journal de Conchyliologie. 63: 91–114. Retrieved 12 July 2020.
  8. Wakefield, A.; McCleery, T. "Three new species of Cystiscus Stimpson, 1865 (Gastropoda: Cystiscidae) from the Tuamotu Archipelago". Novapex. 6 (1–2): 19–30. Retrieved 12 July 2020.
  9. May, W.L. (1911). "New marine Mollusca". Papers and Proceedings of the Royal Society of Tasmania. 1910: 380–398, pls 13–15. Retrieved 17 July 2020.
  10. Tate, R.; May, W.L. (1900). "Descriptions of new genera and species of Australian Mollusca (chiefly Tasmanian)". Transactions of the Royal Society of South Australia. 24 (2): 90–103. Retrieved 17 July 2020.
  11. Pritchard, G.B.; Gatliff, J. H. (1899). "On some new species of Victorian Mollusca". Proceedings of the Royal Society of Victoria, new series. 11 (2): 179–184, pl. 20. Retrieved 18 July 2020.
  12. May, W.L. (1915). "Additions to the Tasmanian marine Mollusca, with descriptions of new species". Papers and Proceedings of the Royal Society of Tasmania for the Year. 1915: 75–99, pls 1-8. Retrieved 18 July 2020.
  13. Boyer, F. (2018). "Révision des gastéropodes marginelliformes dans le récifal supérieur des Maldives". Xenophora Taxonomy. 21: 22–47, figs 86-93.
  14. Lussi, M.; Smith, G. (1998). "Family Cystiscidae Stimpson, 1865. Revision of the family Cystiscidae in South Africa with the introduction of three genera and the description of eight new species". Malacologia Mostra Mondiale. 27: 3–23.
  15. Boyer, F. (2004). "Description of a new Cystiscus (Gastropoda: Cystiscidae) from the Mascarene Islands". Journal of Conchology. 38 (4): 355–361.
  • Bouchet, Philippe & Jean-Pierre Rocroi 2005. Classification and Nomenclator of Gastropod Families. Malacologia 47(1-2):1-397.
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